The necessity of using a protective helmet is recognized in respect of many activities, for example, in construction, in contact sports such as football or hockey, in automobile or motorcycle racing, and by pilots of aircraft etc. A wide variety of designs have been used in the past, as will be recognized by practitioners in this art. For example, assorted suspension harness arrangements have been proposed, as have constructions using liners or pads made of one or more shock absorbing materials.
The reader is directed, for example, to Canadian Pat. Nos. 941,607 which issued on Feb. 12, 1974 with Robert W. Viele as inventor, or Canadian Pat. No. 898,451 which issued on Apr. 25, 1972 with Gerard E. Morgan as inventor. The Viele patent discloses a conformable pad which uses elastomeric pellets or particles within a closed container. The particles are covered with a thin coating of lubricant so that the particles will be easily moveable one relative to another. As noted in that patent the conformable pad is described in the context of a ski boot, but "can be used for medical seat cushions or other areas where quick conformability is desired, such as shoe pads, ear defenders (noise suppressors) and the like. A football helmet made to include such a conformable pad is also described."
The Canadian Pat. No. 898,451 describes a sizing means for a helmet, which cooperates with energy absorbing means. The sizing means is described on page 4 as consisting generally of a plurality of air compartments situated over the interior surface of the helmet shell. Energy absorbing material is preferably included within these compartments, and is described as a standard resilient material, such as expanded vinyl, or expanded polystyrene beads of "STYRAFOAM" (a Trademark). As seen from FIGS. 1, 2 and 7 of that patent, the sizing and energy absorbing mechanism is complicated. Accordingly, it is questionable how reliable such a complex structure would be, especially after some usage and time have passed.